This invention relates to cooling mechanisms and more particularly to an apparatus for cooling high-density integrated circuit packages.
With the miniaturized capabilities afforded by the discovery of solid state electronics, various means of dissipating heat generated by solid state components have been developed. One system involves a gas encapsulated cooling module which utilizes inert gas having a good thermal conductivity as the encapsulated medium in combination with a conductive heat transfer arrangement.
U.S. Pat. No. 4,381,032, discloses a base on which a high-density circuit package is nestingly mounted. A heat exchanger is mounted on the base so as to sealingly enclose the circuit package. The heat exchanger includes a rigid housing having a downwardly opening coolant chamber which is enclosed by a thin wall metallic diaphragm that rests in thermally conductive contiguous contact with each of the dice of the integrated circuit package. A liquid coolant is circulatingly moved through the coolant chamber which biases the diaphragm into conductive contact with the dice in addition to carrying away the heat generated by operation of the integrated circuit package. To insure a more positive contact between the diaphragm and the dice, additional biasing forces are applied to the diaphragm by elastomeric elements, or spring-loaded pistons, provided in the cooling chamber. These elastomeric elements, or spring-loaded pistons, apply their biasing force to localized areas of the diaphragm in contact with the dice of the circuit package. Although this prior art structure is quite efficient, its ability to carry away the operational heat of the operating integrated circuit package is limited by the heat transfer capabilities of the thin-wall diaphragm and the ability of the circulating coolant to absorb the heat transferred thereto by the diaphragm.
To improve on the above heat exchanger, the coolant chamber is filled with thermally conductive spheres so that they are in heat conductive contact with each other and with the membrane which separates the coolant chamber from the circuit packages. The thermal conductivity of the spheroids is superior to that of the coolant. Therefore, the heat conducted through the membrane wall is readily conducted to the spheroids at each point where they are in contact with the membrane, and the heat is similarly transferred to each of the spheroids in that each spheroid is in contact with the several spheroids adjacent thereto. This results in a substantial increase in the heat exchange surface thereby improving the transfer of heat from the circuit packages to the coolant.
Although filling the coolant chamber with thermally conductive spheroids provides an improvement over prior art cooling systems, there is still some loss in cooling efficiency due to the cooling chamber being separated from the source of heat by the thermally conductive membrane wall.
Therefore, a need exists for a new and improved apparatus for cooling high-density integrated circuit packages which overcomes some of the problems and shortcoming of the prior art.